Interaction of Phenol and Cyclohexanol with Supercritical Water

Abstract

Transformation of phenol and cyclohexanol was studied in supercritical water (SCW) in a flow reactor at 300 bar, 500–750°С, and LHSV = 1.2–2.0 h^–1. At 500–600°С the only products of phenol conversion are aromatic hydrocarbons—benzene, toluene, naphthalene and polycyclic aromatic hydrocarbons. Almost complete conversion of phenol is achieved at 750°С with selectivity to gaseous products (H₂, CO₂, CH₄, C₂H₄, C₂H₆) not higher than 30%. A preliminary catalytic hydrogenation of phenol to cyclohexanol facilitates both overall reaction with SCW and the formation of gaseous products. At temperatures as low as 600°С gaseous products are formed from cyclohexanol, and its complete conversion is achieved at 700°С. In the latter case, the yield of the gaseous products reaches 70%, including 40% of C₁–C₂ hydr°Carbons. The differences in the rate of conversion in SCW and in selectivity to gaseous products between phenol and cyclohexanol at 500–750°С are associated with the stability of the aromatic ring.